Anyone witnessing the hand-wringing of parents, the exasperation of schools and the burgeoning multi-million pound "nit-busting" industry could be forgiven for thinking that head lice are a modern epidemic for which there must be something to blame - the demise of the nit nurse, for example.
But nits are an ancient curse. There is evidence of infestation throughout history: a single nit on a human hair dating to around 8000BC was found at a Brazilian archaeological dig. Combs have been recovered from ancient Egyptian tombs and on corpses preserved at Pompeii.
In recent times, the scourge seems worse than ever. But it is also important to get our facts straight. The "nit" in question is not an insect but an empty eggshell. White in colour, one or two glued to a stray hair often go unnoticed. It is only after several weeks that the appearance of scores of grains - scattered like salt behind the ears - sets parental alarm bells ringing. By that time the inhabitants have long since hatched, matured and laid eggs again, not to mention relocated to other handy heads.
The nit nurse is also a bit of a red herring. In many societies, grooming for nits was, and still is, a social activity. There are tableaux on Indian temples showing obedient wives rummaging in their husbands' partings and depictions of families nitpicking with all the festive air of a picnic. Here in the West, thanks to our idea of what constitutes clean living, we have become less keen on the presence of insects in our homes and are therefore less willing to accept that they move in regardless. As a consequence, we do not look for them until it is too late. Just who does the looking - parent, sibling or nit nurse - is irrelevant.
We are more tactile than previous generations, but improvements in healthcare provision and the increasing availability of over-the-counter products mean our knowledge of how to deal with childhood illness and affliction is no longer passed down through families and neighbours. Not only have we forgotten what disease and pestilence looks like, we have lost the ability to prevent it in the first place.
Intermittently in term time - there is no specific nit season as they breed robustly all year round - children are sent home with the "louse letter" informing parents and carers that their child's head should be checked as "cases have been found". This is often accompanied by daunting instructions, sometimes with recipes for remedies containing oils and so on. In truth, the solution is a simple one: comb, conditioner and elbow grease once or twice a week to take control of the problem.
Then, of course, there are the myths: for example, that men do not get nits because of their hormones. The truth is simply that they suffer fewer incidences of infestation because they do not put their heads next to those of their children as often as women do. In recent years, I have heard people in authority insist that people with blonde hair do not get nits; that nits prefer clean heads; that nits are confined to poverty and deprivation; that they can be treated with all manner of remedies; or conversely, that they can be ignored into submission. As long as these and other misconceptions persist, those happy beasts will continue to spread, head by head.
Their domination is also ensured by our cultural characteristics. Infestation is affected by the way we educate. Where once all pupils sat side by side in rows of desks in strict silence, now primary schoolchildren are often seated together on a carpet for registration and other interactive group activities; they learn sitting around tables, mentoring each other, and are encouraged to share resources. Teamwork often means piling in together, not queuing up to compete.
The relaxation of social behaviour seen in (cue parental shudder) the rise of the sleepover, has also greatly added to our experience of infestation. When I was small, we only ever stayed at other people's houses during emergencies or weddings and even then it was on a frayed camp bed in a quiet corner, not jammed six abreast on the floor in bright sleeping bags with bowls of home-popped corn and a stack of DVDs for entertainment. And we as parents, carers and teachers are frantically organising gangs of kids in lift-shares and walking-buses, taking it in turns to herd them to swimming lessons, art club, tae kwon do and so on. Even the upright Baden- Powell world of badges and camps is now less regimented and more user- friendly. And lice love informality.
Children are not afraid of nits but adults are. Paradoxically, we dread them but fail to foresee them. Thankfully we recognise that children thrive in an atmosphere of creativity, fun and mutuality, but in order to achieve this adults are busier than ever. The appearance of unwanted "visitors" always takes us by surprise, causing hysteria, revulsion and cancelled play dates, and has us tearing our hair out at the sheer cost and time spent dealing with them.
But nits will always exist in the community. The solution may be as simple as comb, conditioner and elbow grease once a week, but the point is we should be doing this anyway and not only once an infestation is discovered. Unless we recognise this, and allow a calm sense of inevitability to prevail by adopting a simple, regular grooming routine to control and prevent them, nits will continue to remain an irritation for everyone, as they have done for millennia.
Justine Crow is co-author with Richard Jones of The Little Book of Nits, published by Aamp;C Black.
Key stage 1: Bug busting
Wipe out nits quickly with advice from Community Hygiene Concern.
Key stage 2: Not the nit nurse
How has school nursing changed since the days of the nit nurse? Follow a day in the life of a senior school nurse in a video from Teachers TV.
Key stage 3: In good condition
Learn how to keep hair healthy with Kaza2cov's PowerPoint.
Key stage 4: What's what?
Revise ailments and parasites with pennymcb's card-sorting activity.
Key stage 5: Symptoms spotter
Help students to identify childhood infections with iaveter's presentation.